The present invention relates to a finisher capable of receiving copy sheets sequentially driven out of a copier, facsimile apparatus, printer or similar image forming apparatus, and finishing the sheets stacked therein. More particularly, the present invention is concerned with a finisher capable of selectively stapling a sheet stack at its center and then folding it double or simply stapling the sheet stack at its corner or edge portion.
A finisher of the type described is extensively used with an image forming apparatus. Japanese Patent Publication No. 8-28788, for example, teaches a system capable of recognizing a direction in which stapling means acts on a sheet stack, i.e., whether it acts on the front of a sheet stack or the rear of the same. The system controls, based on the recognized direction, reading means such that image data are read out of a storage in a particular order of page. With this system, it is possible to staple, without regard to the acting direction of the stapling means, a sheet stack from the first page side which is turned over often, thereby reducing damage to the recording materials.
Driving a staple into a sheet stack from the first page side, as stated above, is desirable because the opposite ends of the staple are bent at the rear of the stack and provides the stack stapled at its corner with attractive appearance. However, there is an increasing demand for a finisher capable of stapling a sheet stack at its center, particularly one capable of accommodating sheets of various sizes.
Technologies relating to the present invention are also taught in Japanese Patent Laid-Open Publication No. 6-286358.